Large diameter silicon carbide single crystals and apparatus and method of manufacture thereof
In an apparatus and method growing a SiC single crystal, a PVT growth apparatus is provided with a single crystal SiC seed and a SiC source material positioned in spaced relation in a growth crucible. A resistance heater heats the growth crucible such that the SiC source material sublimates and is transported via a temperature gradient that forms in the growth crucible in response to the heater heating the growth crucible to the single crystal SiC seed where the sublimated SiC source material condenses forming a growing SiC single crystal. Purely axial heat fluxes passing through the bottom and the top of the growth crucible form a flat isotherm at least at a growth interface of the growing SiC single crystal on the single crystal SiC seed.
1. A physical vapor transport (PVT) growth apparatus for PVT growing a SiC single crystal comprising:
a growth crucible having a side, a top, and a bottom, and an aspect ratio of an outside diameter over a height between 1 and 4, the top of the growth crucible configured to support a single crystal SiC seed in an interior of the growth crucible;
insulation surrounding an exterior of the growth crucible, said insulation including side, top, and bottom insulation pieces positioned adjacent the respective side, top, and bottom of the growth crucible, the insulation further including an insulation insert positioned in an opening in the top insulation piece, wherein the insulation insert has a thickness less than a thickness of any one of the side, top, and bottom insulation pieces; and
a heater positioned within the insulation surrounding the exterior of the growth crucible exclusively between a bottom of the growth crucible and the bottom insulation piece, wherein a geometry of the insulation insert is tuned to control heat flux in the SiC single crystal that grows on the single crystal SiC seed in use of the PVT growth apparatus.
2. The PVT growth apparatus of claim 1 , wherein the insulation insert has a thickness between 20 mm and 50 mm and a diameter between 90% and 120% of a diameter of the single crystal SiC seed.
3. The PVT growth apparatus of claim 1 , further including a growth chamber in which the growth crucible, insulation, and heater are positioned, the growth chamber including a top in spaced relation to the top of the growth crucible, wherein at least an interior facing surface of the top of the growth chamber is black in color.
4. The PVT growth apparatus of claim 1 , further including at least one of the following: a window in the bottom insulation piece; and a window in the heater.